Electrosurgical device

ABSTRACT

An electrosurgical device in which high frequency electrical energy powers a cutting electrode. Radio frequency energy is set up in a driver coil which can be in a male member. A female handpiece member can be removably mounted on the male member. A handpiece coil in the handpiece member is energized by the driver coil to energize a surgical electrode connected to one end of the handpiece coil. A return path from a patient is formed by coupling between the patient and the handpiece coil. The handpiece element can be readily removed from the male member so that another handpiece element can be substituted. A releasable electric connection is formed when the male member is inserted in the handpiece element to connect the end of the handpiece coil remote from the surgical electrode to ground.

United States Patent [191 Gonser ELECTROSURGICAL DEVICE [75] Inventor: Donald I. Gonser, Forest Park, Ohio [73] Assignee: Dentsply International Inc., York,

[22] Filed: Nov. 30, 1972 [21] Appl. No.: 310,830

Related US. Application Data [63] Continuation-impart of Ser. No. 214,044, Dec. 30,

1971, abandoned.

[56] 1 References Cited 1 UNITED STATES PATENTS 3,601,126 8/1971 Estes l23/303.14

3,089,496 5/1963 Degelman.... 128/303.l4 2,835,254 5/1958 Coles 128/303.14 3,058,470 10/1962 S eeligner et al. 128/303.l4

3,478,744 11/1969 Leiter ..l28/303.14

[451 Apr. 16, 1974 3,658,067 5/1972 Bross 128/303.l4-

[ 5 7] ABSTRACT An electrosurgical device in which high frequency electrical energy powers a cutting electrode. Radio fiequeaey energy is's e'tnpin amer eafiwmch 555 be in a male member. A female handpiece member can be removably mounted on the male member. A handpiece coil in the handpiece member is energized by the driver coil to energize a surgical electrode connected to one end of the handpiece coil. A return path from a patient is formed by coupling between the patient and the handpiece coil. The handpiece element can be readily removed from the male memberso that another handpiece element can be substituted. A releasable' electric connection is formed when the male member is inserted in the handpiece element to con-. nect the end of the handpiece coil remote from the surgical electrode to ground.

12 Claims, 9 Drawing Figures PATENTEDAPR 16 974 SHEET 3 0F 3 1 ELECTROSURGICAL DEVICE This is a continuation-in-part of my copending appli cation Ser. No. 214,044 filed Dec. 30. 197 l now abandoned.

This invention relates to an electrosurgical device. More particularly, this invention relates to a multipurpose electrosurgical device.

An object of this invention is to provide a radio frequency electrosurgical device in which a surgical electrode can be energized by a handpiece coil connected thereto, which handpiece coil, in turn, is energized by a separate driver coil coupled thereto, the radio frequency energy being supplied through a transmission line from a radio frequency power source.

Briefly, the invention provides an electrosurgical device which includes a source of radio frequency energy which is coupled to a driver coil located in a driver element. A handpiece element includes a second coil which can be removably mounted on the driver element so that an oscillating current of the same frequency is set up in the handpiece coil. A surgical electrode is connected to one end of the handpiece coil. A single electric connection is made between the handpiece element and the driver element to provide a ground return pathway for the other end of the handpiece coil. A capacitance coupling between the body of a patient and the handpiece coil can supply a return electric path when the electrode is brought into engagement with or close proximity to the patients tissues at an area to be cut or otherwise removed, coagulated or carbonized.

The above and other objects and features of the invention will be apparent to those skilled in the art to which the invention pertains from the following detailed description and the drawings in which:

FIG. I is a view in side elevation of an electrosurgical device constructed in accordance with an embodiment of this invention;

FIG. 2 is an enlarged fragmentary view in lengthwise section of the device shown in FIG. 1;

FIG. 3 is a top plan view of a driver element of the device;

FIG. 4 is a top plan view of a handpiece element of the device;

FIG. 5 is a view in enlarged section taken on the line 55 in FIG. 2;

FIG. 6 is a fragmentary view in section taken on the line 6-6 in FIG. 5;

FIG. 7 is a perspective view of a connector ring of the device before mounting thereof;

FIG. 8 is a fragmentary somewhat schematic view of the device in association with a patient and a surgical table on which the patient is disposed, the surgical table being shown in section; and

FIG. 9 is a schematic wiring diagram for the device.

In the following detailed description and the drawings, like reference characters indicate like parts.

In FIG. 1 is shown an electrosurgical device 14 which includes a driver element 16 and a handpiece element 17. The driver element 16 (FIG. 3) includes an outer dielectric tube 18 and a dielectric head end member 19. A shoulder 20 (FIG. 2) on the member 19 is engaged by the left-hand end of the tube 18; The member 19 has a lengthwise bore 21 along which an insulated shielded cable 22 extends. The bore 21 extends from a left-hand end of the member 19 as shown in FIGS. 2 and 3 to an opening 24 through which an end portion of the cable 22 extends into an open chamber 26 inside the tube 18. An insulated sheath or shield 27 of the cable 22 terminates inside the chamber 26. The sheath can include a body of woven conducting metal or the like covered by an appropriate outer coating or cover of dielectric material. The dielectric cover prevents touching of the metal of the sheath by the operator or the patient to prevent injury which might be caused by inadvertent contact with the conducting sheath. The body of the sheath 27 is grounded in the electrical portion of the device as shown in FIG. 9. A short lead 28 (FIG. 2) is connected to an end portion of the body of the sheath 27 inside the chamber 26 and extends outwardly through an opening 29 in the tube 18 to be attached to a connector ring 31 mounted on the tube 18. As shown in FIG. 7, the ring 31, before assembly, is provided with an opening 32 in which the lead 28 (FIG. 2) is attached, as by soldering. The ring 31 is formed of conductive metal such as copper or brass. An opening 33 (FIG. 7) in the ring 31 receives a pin 34 (FIG. 2) which holds the ring 31, the tube 18, and the member 19 in assembled relation. A brass rod 36 is mounted in an axial socket 37 in the member 19 and extends to the right from the member 19 as shown in FIG. 2. A tubular electromagnetic core 38 is mounted on the' rod 36. A driver coil 39 is wound on the core 38. A first lead 41 from the shielded cable 22 is connected to one end of the driver coil 39. A lead 42 connects the opposite end of the driver coil 39 to the right-hand end of the brass rod 36. The other end of the rod 36 is attached to a second lead 422 of the shielded cable 22. As shown, the left-hand end of the socket 37 opens into the chamber 26 to expose the left-hand end of the rod 36. A plug 43 of a dielectric resin is molded in and closes the right-hand end of the tube 18. The left-hand end of the member 19 is provided with circumferential grooves 431 to render it convenient to grip. Electrical components, to be described in detail hereinafter, set up an oscillating high frequency potential across the leads 41 and 422 to energize the driver coil 39.

The handpiece element 17 includes an inner tubular member 44 of dielectric material on which a handpiece or surgical work coil 46 is wound. An exterior dielectric shell 47 surrounds the handpiece coil 46. A right hand end portion 470 of the shell 47 (FIG. 2) is flanged inwardly to engage the right hand end portion of the tubular member 44. The left hand end of the member 44 is flanged outwardly at 471 to engage the inside of the shell 47. A plug 48 of dielectric material is disposed inside the right hand end portion of the tubular member 44. A chuck body 49 is mounted in the plug 48. A lead 51 connects the right hand end of the handpiece coil 46 to the chuck body 49. Chuck jaws 52 are drawn together upon the shank of a surgical electrode 54 by action of a head 56 threaded on the jaws 52 so that the surgical electrode 54 is electrically connected to the right hand end of the handpiece coil 46. A dielectric cap 57 surrounds the head 56. A screw fastener 58 holds the shell 47, the tubular member 44 and the plug 48 in assembled relation. The left hand end of the handpiece coil 46 is connected to a lead 59. An end portion 61 of the lead 59 is attached to a contact loop 72 of spring brass or the like. The contact loop 72 extends through openings 73 and 74 in the tubular member 44. Ends of the loop 72 are soldered together and to the end portion 61 of the lead 59 by solder 76. When the driver element 16 is disposed inside a central socket 77 in the probe element 17, the contact loop engages the ring 31 as shown in FIG. 6 so that the left hand end of the handpiece coil 46 is connected to the ring 31 and, through the ring 31, to the shield 27 and ground. The contact ring 31 engages an annular shoulder 78 inside the tubular member 44 of the handpiece element, and the contact loop is gripped against the ring 31 at the shoulder 78, the material of the tubular member 44 being resilient and being deformed as shown at 79 to cause firm engagement between the contact loop 72 and the contact ring 31.

In FIG. 9 is shown schematically the wiring diagram of the device. Alternating current power is supplied by power leads 111 and 112. A power line radio frequency interference filter 113 including condensers 114 and 115 and inductances 116 and 117 greatly attenuates radio frequency feed-back to the power leads. A power line fuse 118 is provided in the lead 111.

From the power line filter 113, one lead 119 is connected to one side of a primary winding 121 of a transformer 122. A second lead 123 from the power line filter 113 is connected to one pole 124 of a double pole double throw on-off switch 126. The switch 126 is shown in the on position in full lines. In this position, the lead 123 is connected to a lead 127 which extends to a single pole single throw interlock switch 128. The interlock switch 128 is closed during operation of the device but can be arranged to be caused to open when a casing of the device (not shown) is opened. The switch 128, when closed, connects the lead 127 to a lead 129 connected to the opposite end of the primary winding 121 to power the transformer 122. A panel light 130 connected across the leads 119 and 129 indicates that the primary winding 121 of the transformer 122 is powered. A second pole 131 of the switch 126, when in the on position, connects leads 132 and 133 to connect one side of a heater electrode 134 of a tetrode main power amplifier tube 136 to one side of a first secondary winding 137 of the transformer 122, which can be constructed to produce approximately 6 volts AC to the heater electrode 134. The other side of the first secondary winding 137 is connected to ground as is the opposite side of the electrode 134. A fan motor 1371 is also connected across the leads 119 and 129 to drive a fan 1372 which blows air on the tetrode 136 and other components to cool the tetrode and other components. When the on-off switch 126 is swung to its off position, the first pole 124 connects the lead 123 to a lead 139 which is connected to one side of a primary winding 141 ofa transformer 142. The other side of the primary winding 141 of transformer 142 is connected to the lead 119 so that the primary winding 141 of transformer 142 receives line voltage. One side of a secondary winding 144 of the transformer 142 is connected through a lead 145 and the second pole 131 of the on-off switch 126 to the heater electrode lead 132 so that the heater electrode 134 is heated not only when the on-off switch 126 is in the on position but also when the on-off switch 126 is in the off position. The secondary winding 144 of the transformer 142 can be arranged to deliver about four volts so that the heater electrode 134 is heated but at a lower temperature when the switch 126 is in the off position but is maintained at a sufficient temperature that the device will operate at once when the switch 126 is turned on.

A second secondary winding 146 of the transformer 122 suppies a voltage of approximately 2,000 volts AC across leads 147 and 148 to a full wave bridge rectifier 149 which supplies 2,000 volts direct current across leads 150 and 151. The lead 150 is connected to ground as is a cathode 152 of the tetrode 136. The lead 151 is connected through a plate choke 153 and a parasitic suppressor network 154 to a plate 156 of the tetrode 136 so that 2,000 volts DC is impressed between the cathode 152 and the plate 156 of the tetrode 136. A filter condenser 157 smooths out wave form ripple from the rectifier 149. An adjustable resistor 159 and a fixed resistor 159A are connected in series across the leads 150 and 151. A lead 158 connected to the tap of the adjustable resistor 159 supplies a positive potential through a resistor 161 and a lead 162 to a screen grid of the tetrode 136. A voltage of approximately 350 volts can be taken off at the tap which is reduced to approximately 300 volts at the screen grid. An appropriate resistance 164 bleeds'off screen grid current to ground. A capacitor 166 connected between the screen grid lead 162 and ground removes or shunts out radio frequency from the screen grid.

A section 146A of the second secondary winding 146 of the transformer 122 is connected in parallel with a capacitor 1468 to form a tuned circuit tuned to a line input frequency, which can be 60 Hertz, to stabilize the secondary winding voltages to a variation of approximately :1 percent with a change in input voltage of il5 percent impressed on the primary winding 121. Thus, the transformer 122 is a substantially constant voltage transformer stabilizing all the cicuitry of the device.

A bias voltagefor a control grid 168 of the tetrode 136 is supplied by a third secondary winding 169 of the transformer 122. A first lead 171 from he winding 169 is connected to ground and a second lead 172 from the winding 169 is connected to a rectifier 173. The rectifier 173 supplies a negative potential through a resistance 1741 and an inductance 1742 to a lead 174, which is connected to one end of a first series winding 176 of a transformer 1761. The other end of the winding 176 is connected through a second series winding 1762 of the transformer 1761 and an inductance 1763 to a lead 179 connected to the control grid 168 of the tetrode 136. A condenser 181 which is connected between ground and a junction 1743 between the resistance 1741 and the inductance 1742 smooths out the wave form of the potential from the rectifier 173. A resistance 183 connected in parallel with the condenser 181 serves todischarge the condenser 181 when the device is turned off. The bias voltage can be approximately -l20 volts.

Oscillator circuits 184 and 186 for the device are powered from a fourth secondary winding 188 of the transformer 122. Leads 189 and 191 from the winding 188 are connected to a full wave bridge rectifier 192 which supplies approximately 25 volts DC across leads 193 and 194. A condenser connected across the leads 193 and 194 smooths ripple voltage. A resistance 196 connected across the leads 193 and 194 discharges the condenser 195 when the device is turned off. The lead 193 is connected to ground. The lead 194 is connected to one side of a variable potentiometer 202. The other side of the potentiometer 202 is connected by a lead 204 to a pair of push button switches 2041 and 2042. The lead 204 is' connected to a contact 2043 of ground.

When the push button 2041 is moved to its other position and the lead 204 is grounded, a voltage of 25 volts is impressed across the potentiometer 202 and a selected voltage between zero and 25 volts is impressed upon a lead 206 connected to the tap of the potentiometer 202. The lead 206 is connected through an inductance or choke 207 to the collector of a transistor 208, which is a part of the oscillator circuit 186. The emitter of the transistor 208 is connected to the lead 204, which is connected to ground by the switches 2041 and 2042. The lead 206 is also connected through resistors 209 and 211 and a rectifier 212 to one side ofa tickler coil 213. The rectifier 212 functions to reverse bias the base of the transistor 208 and is connected to one side of the tickler coil 213, which is excited by a tank circuit consisting of an inductance 214 and a condenser 216 coupled to the transistor 208 in which continuous oscillation is set up by the tank circuit. The other side of the tickler coil 213 is connected to the base of the transistor 208. The rectifier 212 establishes the reverse bias required by the base of the transistor 208 and is also connected to the lead 204 through a condenser 217 which establishes the bias network circuitry. The lead 204 is connected through a bias rectifier 2171 to a junction between the resistors 209 and 212. The tank circuit is connected with the emitter and the collector of the transistor 208 through a coupling condenser 218. A condenser 219 is connected between the emitter and the collector of the transistor 208 to shunt out radio frequency potentials. A capacitor 777 acts to provide a bypass to ground shunt for attenuating radio frequency feed-back into the line 206 when the oscillating circuit 186 is in operation. The tank circuit can be tuned to oscillate at a rate of approximately 3.5 mega- Hertz. The oscillation is picked up by the transformer winding 1762 and the voltage thereof is multiplied by the transformer winding and impressed by way of the lead 179 on the control grid 168 of the tetrode 136 to provide an amplified output by the tetrode 136 of that frequency. The output of the tetrode 136 is impressed by way of a lead 220 on a series tuned tank circuit which includes condensers 221 and 222 and an inductance 223. A take-off lead 224 which is connected between the condensers 221 and 222 extends to one side of a first matching impedance 226. The lead 422 from the other side of the first matching impedance 226 extends through the grounded sheath or shield 27 and is connected to one end of the driver coil 39. The lead 41 also extends through the sheath 27 to the opposite end of the driver coil 39. The lead 41 is connected to one end of a second matching impedance 234. The other end of the second matching impedance 234 is connected to ground. Thus, a continuous radio frequency oscillating potential is set up in the handpiece coil 46 and in the electrode 54. The series tuned tank circuit consisting of the condensers 221 and 222 and the inductance 223 is matched to the characteristic impedance of the transmission line consisting of the leads 41 and 422 inside the sheath 27 through the matching impedances 226 and 234.

When the switch 2041 is moved to its other position to ground the lead 204, a continuous oscillation is impressed on the coil 39. When the switch 2042 is moved to its other position while the switch 2041 is in the position shown and while a double pole double throw blend switch 2341 is in an off position, at which poles thereof are in an alternate position, the oscillating circuit 184 is energized to produce an interrupted oscillation in the driver coil 39. The oscillatingcircuit 184 is generally similar to the circuit 186 already described and includes a transistor 237, a tank circuit inductance 238, a tank circuit capacitor 239, and a tickler coil 240 and associated elements. A lead 241, which is connected to the tap of a potentiometer 2411 is connected through a choke 242 to the collector of the transistor 237. When the switch 2042 is moved to its other position, a lead 2421 attached to one side of the potentiometer 2411 is connected to ground. The other side of the potentiometer 241 1 is connected through a lead 2422 and a pole 2423 of the switch 2341 to the lead 194 so that a potential of 25 volts DC is impressed across the potentiometer 2411 and a selected potential not exceeding 25 volts is impressed across the lead 241 and the lead 2421 connected to the emitter of the transistor 237 to set the oscillating circuit 184 in operation to deliver an oscillator frequency of approximately 3.5 megaHertz on the control grid of .the tetrode 136. The lead 241 is also connected to base leads of transistors 244 and 246, which form a multivibrator circuit. through resistors 247 and 248, respectively. The collector lead of the transistor 244 is coupled through a condenser 249 to the base of the transistor 246 and the collector of the transistor 246 is coupled through a condenser 251 to the base of the transistor 244. The collectors of the transistors 244 and 246 are connected to the lead 241 through resistors 2511 and 2512, respectively. Emitters of the transistors 244 and 246 are connected to the lead 2421. The multivibrator circuit can be arranged to oscillate at a rate of approximately 7,000 Hertz. A lead 252 from the collector of the transistor 246 is connected through a coupling condenser 253 to the base of the transistor 237 so that the operation of the oscillating circuit 184 is interrupted at a rate of 7,000 Hertz to put an interrupted oscillating potential on the control grid of the tetrode 136 and to supply an interrupted radio frequency oscillating potential at the electrode 54.

An adjustable capacitor 1765 is connected between the left hand of the inductance 1763 and ground and can be adjusted so that it is series tuned with the inductance 1763 so that the grid input is tuned with the plate series tuned circuit 221, 222 and 223. Both of these circuits are tuned with the driver input oscillating circuits 184 and 186 at approximately 3.5 megaHertz. The secondary windings 176 and 1762 of the transformer 1761 combined with a capacitor 2172, which is connected between these secondary windings and ground, constitute a series tuned circuit which also is tuned to approximately 3.5 megaHertz.

Loop feed-back coupling capacitors 1776 and 1777 are connected to winding 1762 through winding 176 and are connected to the bases of the transistors 237 and 208, respectively, for the purpose of stabilizing the transistor outputs at low operating levels and to insure sufficient input base drive for these transistors when oscillating circuits 184 and 186 are operated at a low voltage input level, insuring operation of these circuits at such low voltage potentials.

The switches 2041 and 2042 are so connected that only one of these switches can be effective to cause operation of one of the oscillating circuits at any one time and only one of the oscillating circuits operates at any one time so long as the blend switch 2341 is in its alternate or off position. I I When the blend switch 2341 is disposed in its full line or on position, moving ofthe switch 2041 to its other position energizes both of the oscillating circuits 184 and 186. The oscillating circuit 186 is energized in the same manner as already described. The lead 204, which is connected to ground by movement of the switch 2041 to its other position is connected through a lead 256 and a pole 257 of the blend switch 2341 to the lead 2421 to connect the right hand end of the potentiometer 2411 to ground. The lead 2422 from the left hand end of the potentiometer 2411 is connected through an adjustable resistance 258 to the lead 194 so that a potential is impressed across the potentiometer 2411 which can be no greater than 25 volts and which is determined by the setting of the adjustable resistance 258. A potential is impressed across the leads 2421 and 241 which is controlled by the position of the tap of the potentiometer 2411 and by the setting of the adjustable resistance 258 and lead 206, which is controlled by potentiometer 202 so that both the oscillating circuit 184 and the oscillating circuit 186 are set in operation and an output is provided from the tetrode 136 for energizing the electrode 54 which combines the interrupted oscillation of the circuitl84 with the uninterrupted oscillation of the circuit 186.

When the device is to be used, an appropriate electrode 54 is mounted in the chuck jaws 52 (FIG. 2). The blend switch 2341 is disposed either in the position shown in FIG. 9, at which a blend of interrupted and uninterrupted oscillations is produced, or in its other or off position at which only one of the oscillating circuits 184 and 186 can be used at one time. The driver element 16 (FIG. 2) is mounted inside the probe element 17 with the contact loop 72 engaging the contact ring 31. The main on-off switch 126 is turned on, and the electrode 54 is moved to a position adjacent or touching a patients tissues 301 (FIG. 8) on a surgical table 3011 at a point where electrosurgery is to be performed. The appropriate one of the push button switches 2041 and 2042 (FIG. 9) is moved to its other position to provide a radio frequency current flow in the driver coil 39 which induces a like radio frequency oscillation in the handpiece coil 46. As the electrode 54 touches or approaches the body of the patient, an electrosurgical action is provided at the electrode, and a return electrical path is provided through the body of the patient 301 and through the air gap between the body of the patient and the handpiece coil as indicated by dashed capacitance 302 in FIG. 8. For operative procedures in which moderate or small power up to approximately 150 watts power input to the tissues is required, this capacitance between the patients body and the probe coil provides a sufficient return electrical path. However, if greater power over approximately 150 watts power input to the tissues approaching the maximum power of approximately 400 watts which can be supplied by the device is to be used, it can be desirable to use an ancillary or passive electrode 303 having a relatively large area in contact with the body of the patient as shown in FIG. 8, which is connected through a lead 3031 and capacitance 304 (FIG. 9) to a ground lead of the device. The characteristic impedance of the transmission line consisting of the leads 41 and 422 inside the sheath 27 is matched as closely as possible to the lumped impedance of the driver coil 39, the handpiece coil 46 and patient tissue load when the device is used in cutting, coagulating and dessicating.

When the electrosurgical operation is to be an ordinary or usual cutting action, the blend switch 2341 is disposed in its other or of position, and the push button switch 2041 is moved to its other position to set the oscillating circuit 186 in operation and to provide an uninterrupted oscillation. If a coagulating, dessicating, or fulgurating action is desired, the push button switch 2042 is moved to its other position to cause operation of the oscillating circuit 184 and the multivibrator circuit of the transistors 244 and 246 providing an interrupted oscillation. If a blend of interrupted and uninterrupted oscillations is required, as where very substantial tissue destruction is desired as in some cutting operations, the blend switch 2341 is moved to its full line or on" position, and the switch 2041 is moved to its other position to cause delivery of a blending of interruped and uninterrupted oscillations.

The power delivered by the oscillating circuit 184 can be adjusted by movement of the tap of the potentiometer 2411. The power delivered by the oscillating circuit 186 can be adjusted by movement of the tap'of the potentiometer 202.

With the structure of this invention, a number of probe or handpiece elements can be employed with a single driver element, and change of handpiece elements can be rapidly and conveniently effected.

In the device as shown, the handpiece coil surrounds the driver coil and the return electrical path from the patients tissues is chiefly to the handpiece coil, but, if desired, part or all of the driver coil can be extended outside the handpiece coil to permit a return electrical path to the driver coil.

The electrosurgical device described above and illustrated in the drawings is subject to structural modification without departing from the spirit and scope of the appended claims.

Having described my invention, what I claim as new and desire to secure by letters patent is:

1. An electrosurgical device which comprises a driver element including a driver coil, a transmission line having grounding means and also including two line conductors which are connected to opposite ends of the driver coil, means for impressing a radio frequency oscillating electrical current on the conductors to energize the driver coil, a handpiece element having a socket thereinside, the driver element being removably and slidably received inside the socket of the handpiece element, a handpiece coil in the handpiece element surrounding the socket, means for attaching a surgical electrode to one end of the handpiece coil with a portion of the surgical electrode exposed, contact means on the driver element connected to the grounding means, contact means on the handpiece element at the socket connected to the other end of the handpiece coil and engaging the contact means of the driver element when the driver element is seated in the socket, the energized driver coil located adjacent but spaced from the handpiece coil inducing a radio frequency oscillating electrical current in the handpiece coil, there being electrical coupling between the handpiece coil and a patient when the surgical electrode is brought into proximity with tissues of the patient.

2. An electrosurgical device as in claim l wherein the grounding means in the transmission line is a conducting sheath surrounding the conductors and is connected to ground of the means for impressing a radio frequency oscillating electrical potential.

3. An electrosurgical device as in claim 2 wherein there is a dielectric cover surrounding the conducting sheath.

4. An electrosurgical device as in claim 1 wherein the contact means on the driver element is a metal ring surrounding the driver element and the contact means of the handpiece element is a metal band attached to the handpiece coil and extending through an opening in a wall of the handpicce element into the socket of the handpiece element, resilience of the wall causing the wall to grip the handpiece element contact means to hold the contact means in firm engagement.

5. An electrosurgical device which comprises a driver element including a driver coil, a transmission line including at least two conductors, grounding means, a tubular dielectric member, a dielectric head end member mounted in one end of the tubular member, an electrically conducting rod mounted in the head end member extending along the tubular member substantially axially thereof, and a tubular magnetic core member mounted on the rod, the driver coil being wound on the magnetic core member inside the tubular member, one end of the driver coil being attached to the electrically conducting rod, the transmission line extending through an opening in the head end member into the interior of the tubular member, one of the conductors of the transmission line being connected to the opposite end of the driver coil, the other of the conductors of the transmission line being attached to the electrically conducting rod, means for impressing a radio frequency oscillating electrical current on the conductors to energize the driver coil, a handpicce element having a socket thereinside, the driver element being removably and slidably received inside the socket of the handpiece element, a handpiece coil in the handpiece element surrounding the socket, means for attaching a surgical electrode to one end of the handpiece coil with a portion of the surgical electrode exposed, contact means on the driver element connected to the grounding means, contact means on the handpiece element at the socket connected to the other end of the handpiece coil and engaging the contact means of the driver element when the driver element is seated in the socket, the driver coil inducing a radio frequency oscillating electrical current in the handpiece coil, there being electrical coupling between the handpiece coil and a patient when the surgical electrode is brought into proximity with tissues of the patient.

6. An electrosurgical device as in claim 5 wherein the transmission line includes a conducting shield surrounding the conductors thereof and the contact means on the driver element is a ring surrounding the tubular dielectric element and connected to the conducting shield.

7. An electro surgical device which comprises a primary driver coil and a secondary surgical work coil which can be assembled together with said coils in adjacent but spaced relation and mutually coupled, the driver coil and the surgical work coil being mounted in separable elements, a radio frequency power source, a transmission line connecting. the radio frequency power source to the driver coil, a surgical electrode, means attaching the surgical electrode to one end of the surgical work coil, and means for coupling the other end of the surgical work coil to the radio frequency power source, there being an electrical circuit completed from the surgical electrode through a patients tissues and at least one of the coils by capacitance coupling with the patient when the surgical electrode is brought into proximity with said patients tissues.

8. An electrosurgical device as in claim 7 wherein the transmission line hasa characteristic impedance electricallymatched to a lumped impedance of the primary driver coil, the secondary surgical work coil, and the patients tissues.

9. An electrosurgical device as in claim 7 wherein power is supplied to the radio frequencypower source by power leads through a substantially constant voltage transformer which stabilizes the radio frequency power source.

10. An electrosurgical device as in claim 7 wherein the surgical work coil element is hollow and the driver coil element is releasably received inside the surgical work coil element.

11. An electrosurgical device as in claim 7 wherein the means for coupling the other end of the surgical work coil to the radio frequency power source includes interconnecting contacts on thc elements and the transmission line includes means for connecting the driver coil contact to the radio frequency power source.

12.- An electrosurgical device which comprises a driver element including a driver coil, a transmission line including conductors connected to opposite ends of the driver coil, means for impressing a radio frequency oscillating electrical current on the conductors to energize the driver coil, a handpiece coil in electrically coupled relation with the driver coil located adjacent to but spaced therefrom, means for attaching a surgical electrode to one end of the handpiece coil with a portion of the surgical electrode exposed, the driver coil inducing a radio frequency oscillating electrical current in the handpiece coil, there being electrical coupling between the handpiece coil and a patient when the surgical electrode is brought into proximity with tissues of the patient. 

1. An electrosurgical device which comprises a driver element including a driver coil, a transmission line having grounding means and also including two line conductors which are connected to opposite ends of the driver coil, means for impressing a radio frequency oscillating electrical current on the conductors to energize the driver coil, a handpiece element having a socket thereinside, the driver element being removably and slidably received inside the socket of the handpiece element, a handpiece coil in the handpiece element surrounding the socket, means for attaching a surgical electrode to one end of the handpiece coil with a portion of the surgical electrode exposed, contact means on the driver element connected to the grounding means, contact means on the handpiece element at the socket connected to the other end of the handpiece coil and engaging the contact means of the driver element when the driver element is seated in the socket, the energized driver coil located adjacent but spaced from the handpiece coil inducing a radio frequency oscillating electrical current in the handpiece coil, there being electrical coupling between the handpiece coil and a patient when the surgical electrode is brought into proximity with tissues of the patient.
 2. An electrosurgical device as in claim 1 wherein the grounding means in the transmission line is a conducting sheath surrounding the conductors and is connected to ground of the means for impressing a radio frequency oscillating electrical potential.
 3. An electrosurgical device as in claim 2 wherein there is a dielectric cover surrounding the conducting sheath.
 4. An electrosurgical device as in claim 1 wherein the contact means on the driver element is a metal ring surrounding the driver element and the contact means of the handpiece element is a metal band attached to the handpiece coil and extending through an opening in a wall of the handpiece element into the socket of the handpiece element, resilience of the wall causing the wall to grip the handpiece element contact means to hold the contact means in firm engagement.
 5. An electrosurgical device which comprises a driver element including a driver coil, a transmission line including at least two conductors, grounding means, a tubular dielectric member, a dielectric head end member mounted in one end of the tubular member, an electrically conducting rod mounted in the head end member extending along the tubular member substantially axially thereof, and a tubular magnetic core member mounted on the rod, the driver coil being wound on the magnetic core member inside the tubular member, one end of the driver coil being attached to the electrically conducting rod, the transmission line extending through an opening in the head end member into the interior of the tubular member, one of the conductors of the transmission line being connected to the opposite end of the driver coil, the other of the conductors of the transmission line being attached to the electrically conducting rod, means for impressing a radio frequency oscillating electrical current on the conductors to energize the driver coil, a handpiece element having a socket thereinside, the driver element being removably and slidably received inside the socket of the handpiece element, a handpiece coil in the handpiece element surrounding the socket, means for attaching a surgical electrode to one end of the handpiece coil with a portion of the surgical electrode exposed, contact means on the driver element connectEd to the grounding means, contact means on the handpiece element at the socket connected to the other end of the handpiece coil and engaging the contact means of the driver element when the driver element is seated in the socket, the driver coil inducing a radio frequency oscillating electrical current in the handpiece coil, there being electrical coupling between the handpiece coil and a patient when the surgical electrode is brought into proximity with tissues of the patient.
 6. An electrosurgical device as in claim 5 wherein the transmission line includes a conducting shield surrounding the conductors thereof and the contact means on the driver element is a ring surrounding the tubular dielectric element and connected to the conducting shield.
 7. An electro surgical device which comprises a primary driver coil and a secondary surgical work coil which can be assembled together with said coils in adjacent but spaced relation and mutually coupled, the driver coil and the surgical work coil being mounted in separable elements, a radio frequency power source, a transmission line connecting the radio frequency power source to the driver coil, a surgical electrode, means attaching the surgical electrode to one end of the surgical work coil, and means for coupling the other end of the surgical work coil to the radio frequency power source, there being an electrical circuit completed from the surgical electrode through a patient''s tissues and at least one of the coils by capacitance coupling with the patient when the surgical electrode is brought into proximity with said patient''s tissues.
 8. An electrosurgical device as in claim 7 wherein the transmission line has a characteristic impedance electrically matched to a lumped impedance of the primary driver coil, the secondary surgical work coil, and the patient''s tissues.
 9. An electrosurgical device as in claim 7 wherein power is supplied to the radio frequency power source by power leads through a substantially constant voltage transformer which stabilizes the radio frequency power source.
 10. An electrosurgical device as in claim 7 wherein the surgical work coil element is hollow and the driver coil element is releasably received inside the surgical work coil element.
 11. An electrosurgical device as in claim 7 wherein the means for coupling the other end of the surgical work coil to the radio frequency power source includes interconnecting contacts on the elements and the transmission line includes means for connecting the driver coil contact to the radio frequency power source.
 12. An electrosurgical device which comprises a driver element including a driver coil, a transmission line including conductors connected to opposite ends of the driver coil, means for impressing a radio frequency oscillating electrical current on the conductors to energize the driver coil, a handpiece coil in electrically coupled relation with the driver coil located adjacent to but spaced therefrom, means for attaching a surgical electrode to one end of the handpiece coil with a portion of the surgical electrode exposed, the driver coil inducing a radio frequency oscillating electrical current in the handpiece coil, there being electrical coupling between the handpiece coil and a patient when the surgical electrode is brought into proximity with tissues of the patient. 